In the farm industry, seed cleaners are utilized to separate dust, dirt, weed seeds, and other fine debris from the desired commodity seed. For this purpose, a seed sifting or screening mechanism is employed. The screening mechanism typically provides a screen along an inclined plane which is agitated in a generally gyratory or oscillatory path. The particulate material to be cleaned is introduced onto the upper surface of the screen and vibration causes the particulate material to be conveyed along the screen surface. The movement of the particulate material along the screen causes the fines, such as the dust or other waste material, to be discharged through the apertures of the screen while the overs, such as the commodity seed, is collected at the end of the screening surface for further treatment or removal from the apparatus.
One of the problems associated with using a vibrating screen to separate particulate material is that the apertures of the screen often become clogged with particulate matter thereby reducing the efficiency of the cleaning operation. To dislodge material from the screen apertures, various cleaning mechanisms have been employed. For example, brush assemblies have been employed in which motor driven brushes are swept along the under surface of the screens to dislodge the particles from the screen apertures. However, the drive mechanism operating the brushes is subject to wear and breakage. Further routine servicing is required to maintain the normal operation of the drive mechanism. In addition, periodic replacement and cleaning of the brushes is also required.
To obviate these difficulties, cleaning of the screen apertures has been effected through the use of screen impacting balls loosely supported underneath the screen in a container which is affixed or attached to the screening surface. The impacting balls are simultaneously agitated with the screen assembly. Through continual impact with the screen, the impacting balls function to loosen and dislodge debris from the apertures of the screen.
To efficiently process various types of seeds or other particulate material through the separating apparatus, screens employing different sized apertures are required to enable the user to efficiently match a particular screen with the particulate material being processed. If the container for the impacting balls is attached or affixed to the screen, screen replacement to accommodate a different type of particulate material becomes difficult and time consuming. Either a separate ball tray container must be provided with each screen, or the ball tray container must be detached from the original screen by removing the container fasteners and then reattaching the container to the selected replacement screen. This change over procedure is cumbersome and inefficient. If the screens are not frequently changed, the fasteners are often difficult to remove due to rusting or various other factors. In addition, conventional fasteners can be easily lost or misplaced in a farm environment.
The efficiency of operation of a conventional seed cleaning and separating apparatus employing a brush-type cleaner may be increased by retrofitting the brush mechanism with a ball tray container having impact balls, thereby eliminating the brush mechanisms that is subject to servicing or breakage. However, if the ball tray containers for the impact balls are conventionally attached or affixed to the individual cleaning screens, such an arrangement is not desirable, as previously noted, due to the inherent inefficiencies when changing the screens to accommodate different types of particulate material.